(~ I b'~~ No . J-.t5'E Stratigrap'y of Parts of , De Soto and Hardee Counties, Florida By M. H. Bergendahl Trace Elements In-vestigations Report 45B j UNITED STATES DEPAR1~MENT OF TI-IE INTERIOR GEOLOGICAL SURVEY G~olo~J and Mineralogy This document consists of 58 pages, plus 8 plates. Ser1.es A UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY STRATIGRAPHY OF PARTS OF DE SOTO ANL HARDEE COUNTIES, FLORIDA* By lVl . H. Bergendahl April 1954 Trace Elements Investtgations Report 458 This preliminary report is distributed without editorial and technical review for confor mity with official standards and nomenclature. It is not for public inspection or qbotation. *This report concern work done on behalf of the Division of Raw· Vlaterials of the U. s .. Atomic Energy Commission. 2 USGS - TEI-458 GE OLOGY AND MINERALOGY Distribution (Series A) No. of copies Atomic Energy Commission, \'lashington . • • • • • • • • • 2 Division of Ravr Materials, Denver • • 0 • • • 0 0 • 1 Division of Raw Materials, Salt Lake City • • • o • o o 1 Division of Raw Materia1s, Washington ••••• o ... o •• 3 Grand Junction Operations Office. • • • .. • • • • • • • • • 1 Technical Information Service, Oak Ridge. 0 6 Tennessee Valley Authortty, Wilson Dam ••••••• 1 Uc S. Geological Survey :: Fuels Branch, Washington .. • • • • • .. • • • • ., 1 General Geology Branch, Denver ••• o o •••• 1 Geochemistry and Petrology Branch, Washington • • 1 Geophysics Branch, Washington .. • • 0 • 0 • • 1 Mineral Deposits Branch, \<la.shington 1 K.. Le Buck, De nver •••••• • 0 .. • 1 W. Lo Emerick, Plant City •• · • 2 G. H. Espenshade, Washiillgton .. 0 1 M.. Ro Klepper, Wq.shihgton • , . 1 R. A.. Laurence, Knoxville •• 1 D., M.. Lemmon, Washington. • • .. • ., " . 1 V. E. McKelvey.? Menlo Park •• 1 A. E. Weissenborn, Spokane •• 1 TEPC O, Denver • ., • • .. .. ' . 2 TEPCO, RPS, \-lashington o 3 (Including master) 34 3 CONTENTS Page Abstract Introduction .. g Purpose and scope 6 Methods of investigation. 8 Culture 9 Topography. 10 Drainage. 10 Acknowledgments .11 Stratigraphy o 11 Miocene series. 11 Hawthorn formation. 11 :Lithology • 14 Distribution. 16 Details and fauna 16 Or.igin .. 20 Sand of late Miocene age 21 Lithology • 23 Fauna 23 ·Distribution. 2.4 Details 25 Origino 28 Miocene·-Pliocene s eries 29 Undifferentiated phosphatic sand and clay. 29 Lithology • 31 Fauna 31 Dlstribution. 33 Details 33 CT.c:i.gin . 35 Pliocene serles 39 Caloosahatchee marl. 39 Lithology . 40 Distribution. 40 Details and fauna ~1 Origin. ~~3 Pleistocene series. ~3 Deposits of Pleistocene age~ 45 Lithology • '-~· 5 Fauna 1~6 Distribution. 49 Origin. 49 Sediments of Recent age 50 Mechanical analysis. 51 Geologic history • 53 Miocene events . -53 Pliocene events 54 Pleistocene events .. 54 Recent events 55 Economic considerations .. 55 Literature cited • 57 4 ILLUSTRATIONS Page Plate 1. Geologic map of parts of Hardee and De Soto Counties, Florida o • o • ., .. • • .. • , In ·envelope 2. Geologic cross ... section A-A'; north-south section through Hardee and De Soto Countiesi Florida., • o In envelope 3., Geologic cross-section B-B v; eaBt-west section across part .of Hardee County., o ..... o o o ... In envelope 4., Geologic cross-section C-C'; ea.ut-west section across part of De Soto County • • .. " .. .. " • • • In envelope 5.. Geologic crossc.. section D-D 1 j ea.Ht-west section across southern DeSoto County .. o • o .......... In ·envelope 6. Subsurface contour map of Hawth()rn formation and Noca. tee san do ., o .. · • .. • ., .. o • • • • • • .. In envelope 7.. Map showing locations of outcrops, drill holes., .. In envelope 8.. Cumulative frequency curves of munples from 12 auger holes ~ ., .. .. o .. , .. o e o • • o • o o e .. In envelope Figure 1. Index map of land- pebble phospluLte district, Hardee and De Soto Counties~ Florida • .. • • • • • • .. • .. " ·· 7 2. Classification of the upper Tertiary rocks in Florida;~ shovTing stratigraphic terms used by various authors • • " 0 • 0 " • • • • 0 e • • 0 " 13 3 o SUIDlDB.ry of exposed formations in Hardee and De Soto · Counties, Florida • o ., ••• o 15 4. Diagram showing general stratigraphic relations among the formations in Hardee nnd De Soto Counties, Florida • .. .. .. ., .. .. • • 0 " 17 5. Sketch map and cross-sections of borrow pit 1.6 miles east of Nocatee, De Soto County, Florida.. • • ., 22 6. Sketch of section exposed along west bank of Peace Hiver near Gardner, HardeE~ County • • o ., .. 27 5 STRATIGRAPHY Of PARTS OF PE SOTO AND HARDEE COUNTIES, FLORIDA By Mo Ho Bergendahl ABSTRACT The late Cenozoic stratigraphy of part of central Florida immediately south of the land-pebble phosphate district was studied in detail to determine the southern limit of the economically important Bone Valley formation and its relations wit h marine rocks of late Miocene and Pliocene age in south-central Floridae In addition~ a reconnaissance type appraisal of the phosphate and uranium resources of this area was desiredo The upper Tertiary and Quaternary rocks were mapped, and the economic geology was studied in a general mannero The Hawthorn formation~ of middle Miocene age, is the oldest rock exposedo Undifferentiated phosphatic sand and clay may be composed of t he Bone Valley formation, of late Miocene to Pliocene age; a combination of Bone Valley formation and residuum of weathered Hawthorn formation; or Hawthorn residuum aloneo The Bone Valley formation and residuum of Hawthorn formation appea~ almost identical in cuttings from auger drill­ ing in this areao It was not feasible nor practical to map these two units separately.. The undifferenti&ted phosph~tic sand and clay inter~ fingers with a marine sand of late Miocene age, The Caloosahatchee marl~ of Pliocene age, is present in the southeast corner of the area investigatedo It is apparent that the undifferentiated phosphatic sand and clay was undergoing subaerial erosion and reworki~g during deposition o:r -the Caloosahatchee :ma.rlo Stratified sand and clayey sand containing scattered thin lenses of fresh-water limestone and marl of Pleistocene 6 age are either floodplain deposits or subaerial topset beds of a delta made by the Pleistocene Peace Rivero Sediments of Recent age are local stream depositso Bars and shoals in the Peace River south of Brownville, De Soto County, contatn apprec:i.able tonnages of low grade "river-pebble" phosphate .. The phosphate and uranium content of the undii'f'erentiated phosphat i c sand and clay in Hardee County is too low to be of economic significanceo INTRODUCTION Purpose and scope The results of one part of the investigations of the regional geology of central Florida; are presented in this papero Work was done on behalf of the Raw Materi als Division, U. So Atomic Energy Commission. Within the Florida land.-pebble phosphate district ( figo 1) JJ detailed studies have been made of the mineralogy) thickness, phosphate content J> and distribution of the sediments containing the economic concentrations of phosphate nodules . This unpublished work, which was done by geologists of the U .. s .. Geological Survey, was primarily of an economic nature, and little attention was given to the genesis of the phosphate deposits and to regional stratigraphy .. The geology of Hardee and De Soto Counties, which are immediately south of the phosphate mining district, has been described in a number of reports of a regional or statewide scope o No detailed work in this area has been publishedo The southern extent of the formation tha t contains the economic phosphate deposits, t he Bone Valley for mation)) - ,...... ~PLptN/fTIDI'I/ lf/jl A PPR OltJM/17€ W .4\1~~,. 111" LAI'Ip-PE8tJ't? PtfOSPHJtTt' JVIII'Itlif(j PtSTNI(T ...J-./4 I " ,., FIG. 1 INDEX NAP OF LAND- PEBBLE PHOSPHATE DISTHICT A~ill HARDEE AND DE SOTO COUNTIES, FLORIDA. has never been accurately mapped. The northern limit of the Ca loosahatchee marl, a fossiliferous shallow vrater marine rock of Pliocene age -vrhich is present throughout southern Florida, was not precisely determined.. Cooke (1945, p .. 216, 217) believed that the Bone Valley formation extended south into te Soto County where it merged with the Caloosahatchee marl.. On the other hand, Matson and Clapp (1909), }~tson and Sanford (1913), and Cooke and Mossom (1929) had previously put the contact between the Bone Valley formation and Caloosahatchee marl considerably further north in central Hard,ee ·County& All of these authors agreed that both formations were Pliocene in ageo This investigation was conducted to: lc Clarify the late Cenozoic stratigraphy south of the land-pebble phosphate district, particularly the relations of the Bone Valley formation with the Caloosahatchee marlo 2 o Appraise the potential economic value of the area for phosphate and uranium. Methods of investigati.on The ~rea mapped in Hardee and De Soto Counties is a strip 42 miles long and 15 t o 17 miles wide, roughly parallel to the Peace River (plo l) o It includes about 700 square miles vri thin the approximate boundaries of 27° 2' to 27° 39' north latitude and 81° 40' to 82° 3' west l ongitude., Gardner, whic..h is near the center of the area, is about 58 mi.les airline southeast of Tampa and about 50 miles airline south of Lakelando The region is of such low relief that exposures are limited to the banks of streams and shallow borrow pits. In addition, a mantle of surficial alluvium and wind blown sand effectively conceals the older sediments. Less than 40 outcrops were found; the maximum section was 16 feet thick. To obtain more detailed sub-surface